tape

In offset and letterpress printing, tape is a continuous flexible band, usually made from cotton, synthetic fibers, or leather, that runs on pulleys or drums to transport paper sheets through the printing unit. The tape grips the leading edge of each sheet and pulls it at a precise, consistent speed through the press, ensuring proper registration and timing between the paper and the printing mechanism. Without tape running true, sheets will skew, miss the impression cylinder, or arrive at the wrong moment in the print cycle.

The tape is tensioned across two or more pulleys, typically one driven by the main press motor and others serving as idlers or guides. Tension must be maintained within a narrow range: too loose and the tape slips, causing missed feeds; too tight and it stretches, wears prematurely, and puts load on the motor. Some machines use multiple tapes running in parallel to distribute the gripping force across wide sheets and reduce point loading on any single band.

Construction and wear patterns

Industrial printing tapes often have a rubberized or tacky surface on one side to grip the paper without marking it, and a smooth back. The edges of the tape are the stress points: they take wear as sheets feed across them, and splits or fraying at the edges reduce gripping power and can allow sheets to slip or rotate. A tape showing uneven wear across its width usually signals misalignment of the pulleys or accumulation of paper dust and ink residue.

Replacement is routine maintenance. A worn tape will begin to glaze under pressure, losing grip, or will fray and shed fibers onto the paper. The interval depends on press speed and sheet volume, but even on low-volume machines, tapes typically need changing every few months. When fitting a new tape, it must be spliced end-to-end (the join reinforced to match the tape strength) and the pulleys checked for parallel alignment and true rotation.

The term tape in this context refers specifically to the gripping transport band, distinct from the packing or underlay used to build up the impression cylinder, or from the adhesive tapes sometimes used for setup. In older literature, you may also encounter tympan tape, though tympan itself has a different meaning in modern letterpress. Tape quality and condition are silent indicators of press maintenance: a shop that replaces tape regularly, keeps it clean, and watches for slip is a shop that holds color and registration.